Wiring system for transformers for multiphase furnaces



May 15, 1928. 1,669,453

H. BROCK WIRING SYSTEM FOR TRANSFORMERS FOR MULTIPHASE FURNACES Filed March 15, 1927 Patented May 15, 1928.

UNITED STATES PATENT I orrlcs.

mama 3306!, KNAPSAOK, NEAR COLOGNE, G.

WIRING SYSTEM FOR TRANSFO IOB MULTIPHASI FURNACES.

Application fled larch 15, 1937, Serial No. 176,585,41111 in Germany October 14, 1985.

Multiphase supply mains-such as are most useful for three-phase current-which serve for transmitting energy from transformers to electrically-heated smelting furnaces, can carry extraordinarily high currents, since the voltages employable for smelting furnaces are very limited. The lower the voltages are in relation to the strengths of. current, the more constant is the fusing arcand also the running of the furnace, forexample with combined arc and resistance furnaces. With a given group of alternating current transformers,the latter may consist either of one three-phase transformer or three single-phase transformers-the smallest voltages are obtained upon the low tension side, which lies towards the smelting furnace, by means of the so-called delta-connection. The voltages between each two phases are in this case the same as the 'phase voltages, whilst the current strengths are 1.73 times the current strengths of the phases. The hi h tension sides of the transformers are, as heretofore provided connected up on the delta system of connection and the low tension sides of the transformers are also connected up on the same s stem; the low tension connections being ma e directly at the transformers in 80 accordance with the connections of the phases on the high tension side, as hitherto customary. The three phases thus obtained are then taken to each electrode of the furnace. Detrimental to the power factor of the supply system are, not only the direct transformer connections, but also the singlebase lines to the electrodes; induced b the igh currents the electromagnetic fiel s of the transformer connections, are only incom- 4 pletely compensated, and the single-phase linesnto the electrodes are not compensated at a The invention more particularly described hereafter overcomes the drawback of the uncompensated fields and so gives a better power factor for the network. The invention is illustrated diagrammatically in the that the outwardl -radiated electromagnetic field becomes nu with the technically obtainable juxtaposition of the two conductors. The same applies for the conductors of the other phases. The currents belonging to each electrode-each a commencement and anend of two phases-are not united at thetransformer as formerly, and then led to the electrode in single phases, but are first combined at the corresponding electrode at a value of 1.73 times the current of the phases, which value is only applicable for the mesh-connection with three-phase current.

It will be readily understood that the invention may also be employed for a different number of phase currents as regards the wirin system relating thereto.

I c aim -An alternating current distributing system designed for an electric furnace and wherein it is desired to reduce the self in+ ductance due to the large currents used, which comprises a plurality of transformers, a plurality of electrodes, and wires from the secondaries of said transformers leading to the said electrodes, the lead and return wires of each secondary winding extending to said electrodes in a substantial] adjacent and parallel relation, the wires being connected to the electrodes and to each other through the electrodes.

BROOK. 

